1. Field of the Invention
This invention relates to a transmission for a working vehicle, having a transmission mechanism for transmitting drive from an engine to drive wheels and to a working implement attached to the working vehicle.
2. Description of the Related Art
A working vehicle with a working implement such as a mower unit attached thereto may employ a horizontal engine with an engine output shaft extending horizontally or a vertical engine with an engine output shaft extending vertically. One of the two types of engine is selected according to the specifications of the working vehicle.
Where the horizontal engine is employed, the vehicle may have a transmission with an input shaft extending longitudinally of the vehicle body for transmitting engine drive to the transmission mechanism. Engine drive may be transmitted to the transmission mechanism simply by connecting the input shaft of the transmission to the engine output shaft through an intermediate shaft. On the other hand, where the vertical engine is employed, the vehicle may have a transmission with an input shaft extending in the same direction as the engine output shaft for transmitting engine drive to the transmission mechanism. In this case, engine drive may be transmitted to the transmission mechanism simply by connecting the input shaft of the transmission to the engine output shaft through a transmission belt.
Conventionally, therefore, both the former transmission for the horizontal engine and the latter transmission for the vertical engine are made available and used separately as appropriate. However, keeping two such transmissions of different constructions in stock is a factor to increase manufacturing cost.
The object of this invention is to provide a dual-purpose transmission for a working vehicle, which may be used with both a vertical engine and a horizontal engine.
The above object is fulfilled, according to this invention, by a transmission for a working vehicle comprising a transmission mechanism for controlling drive transmission; a first input shaft for transmitting drive from an engine to the transmission mechanism; a second input shaft, usable as an alternative to the first input shaft, for transmitting drive from the engine to the transmission mechanism, the second input shaft extending in a different direction to the first input shaft; an implement-operating output shaft for outputting drive from the transmission mechanism to drive a working implement; and a pair of right and left propelling output shafts for transmitting drive from the transmission mechanism to drive wheels, the propelling output shafts extending in the same direction as axes of the drive wheels.
With this construction, where a horizontal engine is employed as onboard engine, for example, the transmission is installed with the first input shaft extending in the fore and aft direction or longitudinally of the vehicle body, or with the second input shaft extending in the fore and aft direction or longitudinally of the vehicle body. Then, drive from the engine may be inputted to the transmission mechanism only by connecting the engine output shaft to the first input shaft or second input shaft through an intermediate transmission shaft.
Where a vertical engine is employed as onboard engine, the transmission is installed with the first input shaft extending vertically of the vehicle body, or the second input shaft extending vertically of the vehicle body. Then, drive from the engine may be inputted to the transmission mechanism only by connecting the engine output shaft to the first input shaft or second input shaft through a transmission belt.
The first input shaft or second input shaft may be selected as input device for the transmission mechanism by taking the balance of the transmission and posture of the implement-operating output shaft into account. Thus, whichever of the horizontal engine and vertical engine is employed, engine drive may be inputted to the transmission mechanism by means of a simple relay mechanism using an intermediate shaft or transmission belt. In selecting whichever of the input shafts, the ultimate posture of the implement-operating output shaft may also be considered. Drive may be transmitted smoothly to a working implement whether the implement is disposed at a side of the transmission case close to the engine or at the opposite side.
As a preferred embodiment of this invention, it is proposed that the first input shaft and the second input shaft extend transversely of the propelling output shafts, and that the implement-operating output shaft extends in the same direction as the first input shaft. With this construction, when the transmission is placed with the first input shaft or second input shaft extending horizontally or vertically, the propelling output shafts always extend transversely of the vehicle body. Thus, a high degree of freedom is secured for selecting one of the input shafts.
In a further preferred embodiment of this invention, the first input shaft and the implement-operating output shaft may be interconnected through a coupling, and the first input shaft or the implement-operating output shaft and the second input shaft may be interconnected through a bevel gear mechanism. Then, whichever of the first input shaft and second input shaft the engine drive may be inputted to, the drive is outputted straight to the implement-operating output shaft.
When the first input shaft is used to transmit engine drive to the transmission mechanism, the second input shaft made redundant may be detached. This avoids the inconvenience of the unwanted component projecting from the transmission.
Take a mower as an example of working vehicle, varied constructions are employed such as where an engine is disposed at the front or rear of the vehicle body, or where a mower unit is disposed at the front of the vehicle body or in an intermediate portion of the vehicle body. For a working vehicle with the engine position and working implement position frequently changed according to the specifications, the freedom of positioning of the transmission according to this invention is particularly important.
Other features and advantages of this invention will be apparent from the following description of the embodiment to be taken with reference to the drawings.